Adjustable flame burner

ABSTRACT

An adjustable flame burner for an industrial furnace includes a burner body having an apertured refractory baffle forming a forward wall thereof. A fuel duct extends concentrically within the burner body and in registry with a fuel opening in the baffle. An annular chamber is formed between the fuel duct and the burner body and a close-off means is positioned internal of the air chamber to close off certain of the apertures so as to permit adjustment of the flame at all levels of operation. The close-off means can be either movable plugs secured within the air chamber or a partitioned air chamber having a separate air inlet feeding each resultant chamber ahd having alloy tubes connecting from one of the resultant chambers to certain of the apertures. Dual, concentric fuel ducts can be employed with the various close-off means.

United States Patent 1191 Hovis et a1.

[ Nov. 13, 1973 1 ADJUSTABLE FLAME BURNER [75] Inventors: James E. Hovis; Harry P. Finke, both of Pittsburgh, Pa.

[73] Assignee: Bloom Engineering Company, Inc.,

Pittsburgh, Pa.

[22] Filed: Aug. 30, 1972 [21] Appl. No.: 284,956

3,236,460 2/1966 Wood 61a] 239/416.4 3,45 ,334 12/1969 Freyetal 431/12 Primary Examiner-Carroll B. Dority, J1. Attorney-Russell D. Orkin [5 7 ABSTRACT An adjustable flame burner for an industrial furnace includes a burner body having an apertured refractory baffle forming a forward wall thereof. A fuel duct extends concentrically within the burner body and in registry with a fuel opening in the baffle. An annular chamber is formed between ,the fuel duct and the burner body and a close-off means is. positioned internal of the air chamber to close off certain of the apertures so as to permit adjustment of the flame at all levels of operation. The close-off means can be either 1 Reiel'ences Cited movable plugs secured within the air chamber or a UNITED STATES PATENTS partitioned air chamber having a separate air inlet 3,545,903 12/1970 McCullough 431 175 feeding each resultant Chamber ahd having alloy tubes 2,458,542 1/1949 Urquhart 1 431/174 connecting from one Of the resultant chambers to 2,984,296 5/1961 Voorheis 431/187 i of the apertures- Dual, concentric fuel ucts can 3,198,855 8/1965 Suydam 432/12 be employed with the various close-off means. 3,208,502 9/1965 Carlson 431/188 3,209,811 10/1965 Strang 137/610- 7 Claims, 7 Drawing Figures II l7 1 1:24 T v v l I i 38 I 'll I l PAIENTEDNHV 13 ms I Fig.6

SHEET 2. BF 2 Distance from Burner Well Feei Fig. 7

ADJUSTABLE FLAME BURNER BACKGROUND OF THE INVENTION This invention relates to burners and, more particularly, to adjustable flame burners for industrial furnaces.

Large industrial furnaces of the metallurgical type, such as steel soaking pit furnaces and slab or bloom reheat furnaces, require precisely controlled temperature distribution to satisfy subsequent processing operations. In the case of soaking pits for heating steelingots, the burners are normally operated at maximum rated capacity to bring the ingotsup to rolling temperature as fast as possible, at which time the burners are cut back so as to maintain the proper temperature while the ingots are thermally soaked. Early practice wasto reduce air and fuel in essentially proper ratio, thus reducing energy levels accordingly.- Later developments included maintaining the ratio of air to fuel with a high velocity even though the total heat input is reduced. These various practices emphasize the uniformity of temperature during the low energy or soak cycles.

In reheat furnaces, for example, of the side fired walking beam type, a fixed flame burner simply cannot control the temperature distribution since the presence of furnace conditions such as gases going up and gases going through the furnace and different stock sizes and productivity rates create variable flame requirements.

Fixed flame burners are limited in performance where substantial changes in heat release rates or mixing rates are required. Exemplary of this application are blast furnace stove burners.

Our invention permits adjustment ofthe flame characteristics at maximum flow or at reduced flow to suit any particular operating conditions. The temperature profile of the furnace can be controlled at any given flow condition by merely controlling the flame. In the case of soaking pit burners, uniformity of temperature can be controlled during high energy inputs to assure a proper soak out at low energy inputs. For reheat furnaces, the temperature distribution can be precisely controlled irrespective of the furnace and operating conditions, and flame adjustment I permits drastic changes in release rates and mixing rates to occur without resultant changes in flame distribution. Certain flame adjusting mechanisms have been attempted heretofore, but have generally proven unreliable in that the adjusting mechanism is exposed to the furnace heat. For this reason, metal vanes movable into airapertures have proven less than successful.

SUMMARY OF THE INVENTION Our invention is an adjustable flame burner having a burner body and a refractory baffle at the front end thereof. The baffle has a plurality of air apertures in a circular plane thereabout and a central opening for a fuel duct which extends through the burner body. A close-off means is positioned in the air chamber formed between the fuel duct and the burner body to open and close off certain of the apertures. The close-off means is either a number of plugs mounted internally of the air chamber and adapted to seal off certain of the apertures or is a partition wall dividing the air chamber into two separate chambers, each fed by independent air inlets, and alloy tubes connecting one of the chambers to certain of the apertures. Dual, concentric fuel ducts can be employed to further increase the range of flame adjustment.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a section through the adjustable flame burner embodying the partitioned air chamber;

FIG. 2 'is an end view of the burner of FIG. 1; FIG. 3 is an endview of an adjustable flame burner embodying movable plugs;

FIG. 4 is a section taken along line IV--IV of FIG. 3;

DESCRIPTION OF THE PREFERRED EMBODIMENTS The burner, generally designated 10, includes a burner body made up of a metal casing 11 and an adjacent refractory lining 12, FIGS. 1-6. The burner 10 is adapted to be fastened to a wall of a furnace by flanges 13 whichextend outwardly from casing 11 at the forward end of the burner 10. The burner body is closed off at its forward end by a refractory baffle 14 which forms'the forward wall of the burner 10. The rear wall of burner 10 comprises backing plate 15 which also has a refractory lining lfiadjacent thereto. Fuel duct 17 extends through the burner 10 along the'axial center line thereof and is in registry withv a central opening 18 in the refractory baffle 14, FIGS. 14. The fuel duct 17 extends through the backing plate 15 and is adapted to connect to a fuel gas source through standard adjustable connecting valve means. vAn annular chamber 20 is formed between the fuel duct 17 and the refractory lining 12. Chamber 20 isthe conduit for the combustion sustaining gas, such as air.

In the embodiment of FIGS. land 2, the chamber 20 is partitioned into separate chambers 21, and 22 by means of partition wall 23 which extends from the upper rearward surface of casing 11 tothe bottom forwardsurface of. casing 11 Partition wall '23 has a central opening to accommodate fuel duct 17. g

The refractory baffle 14 includes a plurality of air apertures 24 extending therethrough. These air apertures 24, 12 of them in FIG. 2, form a circular plane radially spaced from the fuel outlet 18. The air apertures may be axially parallel with the burner longitudinal axis,*or converging, or diverging, or sk ew'ed to impart'the desired mixing characteristics of. thev combustion sustainmg gas and the fuel. These alternative baffle designs are already known in the art anddo not form a part of this invention. Every thirdgair aperture 24, or four total, communicates with the rearward chamber 22 by means of an alloy tube 25 which extends from an openingin the partition wall 23 to a countersunk portion of aperture 24 on the rearward surface of baffle l4.

' A large air inlet 26 extends through casing 11 and communicates with chamber 21. A'second air inlet 27 of smaller cross section than the large air inlet 26 extends through casing 11 and communicates with chamber 22. The eight apertures 24 are continually in use for purposes of directing the primary air from chamber 21 into contact with the fuel exiting from the fuel duct 17. Depending on the particular flame characteristic desired, air is directed into chamber 22 through air inlet 27 by means of standard valving (not shown). The air passes through the alloy tubes 25 and out apertures 24 to alter the flame characteristics and the resultant temperature profile of the furnace into which the burner is firing.

The close-off means for certain of the apertures 24 of the baffle 14 can be accomplished by means of movable plugs 30 secured within the main air chamber 20, FIGS. 3 and 4. The plugs 30 are shown as cooperating with every third aperture 24 of a nine apertured baffle 14. These plugs 30 are made of a refractory material and are adapted to matingly engage the accommodating recessed rear portion of certain of the apertures 24 along the rear surface of baffle 14. Each plug 30 is positioned at the end of a movable shaft 31 which extends outwardly through an opening in the back plate 15 of the burner. The shafts 31 are slidably mounted in spiders 32 which are clamped to the fuel duct 17. A single air inlet 33 extends through casing 11 to communicate with air chamber 20. The shafts 31 may be manually operated to shut off certain of the apertures 14 or the plugs 30 and shafts 31 can be automatically operated from a control device. Such a control device would be based on the temperature at certain positions in the furnace and would automatically adjust a control valve to open or shut all or certain of the apertures aligned with the plugs.

The embodiments of FIGS. 1 and 2 and FIGS. 3 and 4 can be further adapted to even wider ranges of flame adjustment by means of a concentric inner fuel duct 35 positioned within main fuel duct 17, FIGS. and 6, respectively. The fuel duct 35 is also in registry with the central opening 18 and extends rearwardly through backing plate 15. Where the inner fuel duct 35 and outer fuel duct 17 are employed, a tee-shaped connecting valve 36 is mounted to the rear of backing plate 15. Valve 36 includes an end inlet 37 connecting to inner duct 35 and bottom inlet 38 connecting to outer duct 17. The inner and outer fuel ducts can be used independently or in combination with the adjustable close-off means to create wider ranges of flame adjustment for any given total energy input."

To study the effectiveness of controlling the flame by opening and closing certain of the air apertures independently and in combination with concentric fuel ducts, a series of tests were conducted for a large side fired walking beam furnace in which the center of the furnace routinely ran hot with respect of the side walls. Chromel-Alumel thermocouples were inserted in closed ceramic tubes and positioned-in openings made at intervals along the furnace side walls. The thermocouples were laid directly on the hearth along the horizontal center line. The inside furnace dimensions were 5 feet high by 4 feet wide by 13 and 1% feet long. Water cooled pipes were used in the furnace to provide a constant heat sink for the tests. In addition to measuring temperature, flame lengths were measured both visually and with a UV cell. The design of the adjustable flame burner employed was basically that illustrated in FIG. 6. The testing was conducted with the burner firing at 11 mm btus/hr. with percent excess air. The gas velocity through the inner nozzle was 216 ft./sec. and through the outer nozzle was 104 ft./sec. A standard spinner was employed in the outer nozzle to spin the gas in a direction opposite from the air spin through a baffle having spiral passageways. By plugging off three of the nine air apertures, the flame was altered considerably so as to move the hot spot closer to the burner wall. Specifically in FIG. 7, curve A represents all nine holes open with the gas being directed entirely through the inner nozzle. Curve B represents three of the nine holes plugged with the gas directed through the outer nozzle. Curve C represents three of the nine holes plugged with the gas directed through the inner nozzle and curve D represents all nine holes open with the gas directed through the outer nozzle. The data for curve A was taken after the furnace had been hot soaked and tired for 2 hours, whereas the balance of the data was taken on the furnace after it had been fired for extended periods of time. Plugging the three air apertures at l 1 mm btu/hr reduced the flame length substantially.

The flame length for the burners having three of the air apertures closed was visually detected at 6 to 8 feet and the UV cell gave a signal at 3 feet but no signal at 6 feet. Operating the burners with none of the apertures closed gave a signal at 6 and k feet on the UV cell but no signal at 12 feet.

It can be seen that under a constant energy input, the temperature can vary as much as 200 F at a given point in a furnace depending on the flame characteristic. The control of the flame characteristic thusly provides a means for precise temperature control to satisfy the subsequent processing operations of the stock passing through the metallurgical furnace. In addition, the close-off means is not exposed to hot products of combustion and, therefore, it can operate over the life of the burner.

We claim:

1. An adjustable flame. burner for an industrial furnace comprising a burner body having a refractory baffle forming a forward wall thereof and including a plurality of spaced combustion sustaining gas apertures extending therethrough and positioned in a circular plane radially outward from the baffle central axis and a fuel opening therethrough along the central axis, a backwall, a fuel duct adapted to connect with a fuel source and extending concentrically within the burner body in registry with the fuel opening, an annular chamber means formedbetween the fuel duct and the burner' body including the forward wall thereof, a combustion sustaining gas inlet means cooperating with the annular chamber means, close-off means positioned internal of the air chamber means to close off certain of the apertures so as to permit adjustment of the flame by means unexposed to the furnace interior.

2. The burner of claim 1 in which said close-off means includes at least one plug secured to the burner and positioned within the annular chamber means and movable to open and close certain of said apertures.

3. The burner of claim 1 in which said close-off means includes a partitioned wall partitioning said annular chamber means into a first and second chamber, certain of said apertures communicating with the first chamber and the remainder of said apertures in communication with the second chamber, said inlet means including a first inlet cooperating with the first air chamber and a second inlet cooperating with the second air chamber.

4. The burner of claim 1 including concentric fuel ducts adapted for connection to independent fuel sources.

5. The burner of claim 2 wherein each plug includes a shaft portion slidably positioned within a spider secured to the fuel duct, said shaft extending parallel to the burner body longitudinal axis and through the backwall. I

6. The burner of claim 3 wherein tubular elements extend from the partitioned wall to certain of said aper- 5 tures to communicate the second chamber with said re- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,771,944 Da d November 13, 1973 ln n fl James E. Hovis et al.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

IN THE ABSTRACT:

Line 13, "ahd" should be --and-.

IN THE CLAIMS:

Claim 1 reads as follows:

l. An adjustable flame burner for an industrial furnace comprising a burner body having a refractory baffle forming a forward wall thereof and including a plurality of spaced combustion sustaining gas apertures extending therethrough and positioned in a circular plane radially outward from the baffle central axis and a fuel opening therethrough along the central axis, a backwall, a fuel duct adapted to connect with a fuel source and extending concentrically within the burner body in registry with the fuel opening, an annular chamber means formed between the fuel duct and the burner body including the forward wall thereof, a combustion sustaining gas inlet means cooperating with the annular chamber means, closeoff means positioned internal of the air chamber means to close off certain of the apertures so as to permit adjustment of the flame by means unexposed to the furnace interior."

Claim 1 should read as follows:

-'-1. An adjustable flame burner for an industrial furnace comprising a burner body having a refractory baffle forming a forward wall thereof and including a plurality of spaced combustion sustaining gas apertures extending therethrough and circularly positioned radially outward FORM powso USCOMM-DC 60376-P69 t [1,5, GOVERNMENT PRINTING OFFICE: l9! 0-366-334,

UNITED STATES PATENT OFFICE Page 2 CERTIFICATE OF CORRECTION Patent No. 3,771,944 Dated November 13, 1973 Inventor(s) James E. Hovis et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

from the baffle central axis and a fuel opening therethrough along the central axis, a backwall, a fuel duct adapted to connect with a fuel source and extending concentrically within the burner body in registry with the fuel opening, an annular chamber means formed between the fuel duct and the burner body including the forward Wall thereof, a combustion sustaining gas inlet means cooperating with the annular chamber means, closeoff means positioned internal of the annular chamber means to close off certain of the apertures so as to permit adjustment of the flame by means unexposed to the furnace interior, said close-off means including at least one plug secured to the burner and positioned within the annular chamber means and movable to open and close certain of said apertures relative to the others.

Claim 2 reads as follows:

"2. The burner of Claim 1 in which said close-off means includes at least one plug secured to the burner and positioned within the annular chamber means and movable to open and close certain of said apertures. I

Claim 2 should read as follows:

-Z. An adjustable flame burner for an industrialfurnace comprising a burner body having a refractory baffle forming a forward wall thereof and including a plurality of spaced combustion sustaining gas apertures extending therethrough and circularly positioned radially outward from the baffle central axis and a fuel opening therethrough along the central axis, a backwall, a fuel duct adapted to connect with a fuel source FORM PC4050 $69) USCOMM-DC 60376-P69 UVS. GOVERNMENT PRlNTlNG OFFICE I 1969 Q3$6334,

UNITED STATES PATENT OFFICE Page 3 CERTIFICATE OF CORRECTION Patent No. ,9 D t d November 13, 1973 Inventor(s) James E. Hovis et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

and extending concentrically within the burner body in registry with the fuel opening, an annular chamber means formed between the fuel duct and the burner body including the forward wall thereof, a combustion sustaining gas inlet means cooperating with the annular chamber means, closeoff means positioned internal of the annular chamber means to close off certain of the apertures so as to permit adjustment of the flame by means unexposed to the furnace interior, said close-off means including a partition wall extending substantially diagonally across said annular chamber means to partition it into a first and second chamber, certain of said apertures communicating with the first chamber and the remainder of saidapertures in communication with the second chamber, said inlet means including a first inlet cooperating with the first chamber and a second inlet cooperating with the second chamber.

Claim 3 reads as follows:

"3. The burner of Claim 1 in which said close-off means includes a partitioned wall partitioning said annular chamber means into a first and second chamber, certain of said apertures communicating with the first chamber and the remainder of said apertures in communication with the second chamber, said inlet means including a first inlet cooperating with the first air chamber and a second inlet cooperating with the second air chamber.

Claim 3 should read as follows:

--3. The burner of Claim 1 including concentric fuel ducts adapted for connection to independent fuel sources-- ORM PC4050 H0439) uscoMM-Dc wave-pee U. 5, GOVERNMENT PRINTING OFFICE: 19 0-366-334,

UNITED STATES PATENT OFFICE Page L; CERTIFICATE OF CORRECTION Patent No. 3, 771,944 Dated November 13, 1973 Inventor(s) James E. Hovis et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 4 reads as follows:

"4. The burner of Claim 1 including concentric fuel ducts adapted for connection to independent fuel sources."

Claim 4 should read as follows:

-4. The burner of Claim l.wherein;each plug includes a shaft portion slidably positioned within a spider secured to the fuel duct, said shaft extending parallel to the burner body longitudinal axis and through the backwall.

Claim 5 reads asfollows:

"5. The burner of Claim 2 wherein each plug includes a shaft portion slidably positioned within a spider secured to the fuel duct, said shaft extending parallel to the burner body longitudinal axis and through the backwall.

Claim 5 should read as follows:

-5. The burner of Claim 2 wherein tubular elements extend from the partitioned wall to certain of said apertures to communicate the second chamber with said remainder of said apertures.

Claim 6 reads as follows:

"6. The burner of Claim 3 wherein tubular elements extend from the partitioned wall to certain of said apertures to FORM PC7-1050 (w'sg) USCOMM-DC scam-P09 fi UIS. GOVERNMENT PRINTING OFFICE: 1989 0-366-334.

UNITED STATES PATENT OFFICE Page 5 CERTIFICATE OF CORRECTION Patent 9 Dated November 13, 1973 In n James E. Hovis et al.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

communicate the second chamber with said remainder of said apertures."

Claim 6 should read as follows:

The burner of Claim 2 wherein said first inlet is econd inlet.

substantially larger in cross section than said s Cancel Claim 7.

On the cover sheet, "7 Claims" should read 6 Claims Signed and sealed this 25th day of June 1971;.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Commissioner of Patents Attesting Officer USCOMM-DC 6O376 -P69 u.s. GOVERNMENT PRINTING OFFICE: 19" o3i6-334,

F ORM PO-105O (10-69) 

1. An adjustable flame burner for an industrial furnace comprising a burner body having a refractory baffle forming a forward wall thereof and including a plurality of spaced combustion sustaining gas apertures extending therethrough and positioned in a circular plane radially outward from the baffle central axis and a fuel opening therethrough along the central axis, a backwall, a fuel duct adapted to connect with a fuel source and extending concentrically within the burner body in registry with the fuel opening, an annular chamber means formed between the fuel duct and the burner body including the forward wall thereof, a combustion sustaining gas inlet means cooperating with the annular chamber means, close-off means positioned internal of the air chamber means to close off certain of the apertures so as to permit adjustment of the flame by means unexposed to the furnace interior.
 2. The burner of claim 1 in which said close-off means includes at least one plug secured to the burner and positioned within the annular chamber means and movable to open and close certain of said apertures.
 3. The burner of claim 1 in which said close-off means includes a partitioned wall partitioning said annular chamber means into a first and second chamber, certain of said apertures communicating with the first chamber and the remainder of said apertures in communication with the second chamber, said inlet means including a first inlet cooperating with the first air chamber and a second inlet cooperating with the second air chamber.
 4. The burner of claim 1 including concentric fuel ducts adapted for connection to independent fuel sources.
 5. The burner of claim 2 wherein each plug includes a shaft portion slidably positioned within a spider secured to the fuel duct, said shaft extending parallel to the burner body longitudinal axis and through the backwall.
 6. The burner of claim 3 wherein tubular elements extend from the partitioned wall to certain of said apertures to communicate the second chamber with said remainder of said apertures.
 7. The burner of claim 3 wherein said first inlet is substantially larger in cross section than said second inlet. 